Embodiments of the present inventive concepts relate to an identity-based ring signature scheme, and more particularly, to an efficient identity-based ring signature scheme having a constant number of bilinear pairing computations independent the number of ring members in a verification process and a system performing the method.
A ring signature is a method where a signer composes a group or a ring including him or herself and signs on an arbitrary message by using all of the user's own secret key and a public key of each of other members in the group.
The verification of ring signature may be convinced that the given signature is generated by one of members consisting the ring, but it does not reveal exactly which member of that. Accordingly, a ring signature offers anonymity.
After a concept of ring signature is first proposed by Rivest, Shamir and Tauman in 2001, various ring signature schemes are proposed.
In a public key cryptosystem, a user generally has two keys, e.g., a secret key and a public key. What connects the public key with identity of the public key owner and confirms validity of the public key is a digital signature type of public key certificate on which a certificate authority (CA). In a conventional traditional certificate-based system, each of users have computational complexity to register his public key and verify the validity of a corresponding public key all the time before using the other's public key and the conventional public key system has the issue of key management that is somewhat complex.
Since an identity-based ring signature scheme of Zhang and Kim using a bilinear pairing is proposed in 2002, a lot of identity-based ring signature schemes are proposed. However, the proposed schemes have a feature that bilinear pairing a number of pairing computation increases in proportion to the number of ring members during verification, so that it is considerably inefficient. A bilinear pairing computation on an elliptic curve needs the most time and costs in spite of development of an implementation technology and a computer.